Process for preparing titanium dioxide



W. L. WILSON Dec. 5, 1967 PROCESS FOR PREPARING TITANIUM DIOXIDE Filed July 22, 1965 FIGJ INVENTOR WILLIAM L. WILSON QAM H 5M FIG. '2

ATTORNEYS United States Patent ABSTRACT OF THE DISCLOSURE Pigmentary titanium oxide of improved optical properties is prepared by vapor phase oxidation of titanium tetrahalide with oxygen-containing gas in presence of rutile promoting agent, and at least one source of at least two metallic members selected from Groups IA, IB, IIA, and HE. Optionally, a source of silicon is also present.

This application is a continuation-in-part of copending application U.S. Serial No. 190,140, filed April 25, 1962, now United States Patent 3,214,284, and copending U.S. patent application Serial No. 255,453, filed February 1, 1963.

This invention relates to a process for producing pigmentar'y titanium oxide having superior optical properties by the vapor phase oxidation of a titanium tetrahalide selected from the group consisting of titanium tetrachloride, titanium tetraiodide, and titanium tetrabromide.

Titanium oxide is currently produced commercially by at least two different basic processes, the so-called sulfate process and the chloride process. The latter involves the vapor phase reaction of titanium tetrahalide and an oxygenating gas at a temperature of at least 800 C., usually 1000 to 1400. C., in the absence'or presence of a fluidized bed, e.g., as disclosed in U.S. Letters Patent 2,964,386, U.S. Letters Patent 2,240,343, issued to Mus kat, U.S. Letters Patent 2,394,633, issued to Pechukas et al., or U.S. Letters Patents 2,968,529 and 3,069,281, issued to William L. Wilson. The oxygenating gas may comprise any oxidizing or oxygenating agent, such as oxygen, air, oxides of nitrogen, H 0 oxides of phosphorus, or mixtures of same. Pigmentary titanium oxide has unique optical properties which make it useful, particularly in the paint industry. Such optical properties, for example, tinting strength and'undertone, are a function of particle size, dispersion and color. Pigmentary'titanium oxide of a given particle size distribution range, e.g., mean diameter of 0.2 to 0.5 micron, may be prepa'red'by the vapor phase oxidation processes of Muskat, Pechukas, or Wilson, noted hereinbefore, as well as by other processes, e.g., Canadian Patent 517,816, issued to Krchma et al., or British patent specifications 876,672 and 922,671.

/ However, it has been discovered that the surface activity of the titanium oxide particles produced by the aforementioned processes may be such that electrostatic charges or forces are set up between individual particles whereby the particles come togetherand combine in groups-oi two or more? Such grouping is termed chaining or aggregation. The result of such grouping, chaining, or aggregation is a deficient pigment having less than optimum dispe'rsibility and decreased optical properties, particularly undertone and tinting strength.

It has been discovered that if titanium oxide is prepared in accordance with the present invention, there is produced 'a titanium oxide particle having optimum pigmentary properties, particularly tint tone and tinting strength, for a given particle size distribution range. More particularly, there is produced a raw, uncoated pigmentary titanium oxide particle having high, superior dispersion, a tinting strength of at least 1600, usually at least 1700, and a blue Patented Dec. 5, 1967 undertone (tint tone) for a particle size distribution range below 1.0 micron in mean diameter, preferably 0.2 to 0.5 micron, with a final tinting strength of at least 1780, usual- 1y above 1800, when the raw pigment is wet coated with metal oxides, as disclosed by U.S. Patent 3,146,119, or copending U.S. application Serial Number 370,349, filed May 26, 1964.

In the broad practice of this invention, a rutile titanium oxide pigment of superior pigmentary properties is produced by the vapor phase reaction of a selected titanium tetrahalide with an oxygen-containing gas in the presence of a source of a small, effective amount of rutile promoting metallic agent and a small, effective amount of at least one source of at least two metallic members selected from the Groups IA and IB having an atomic weight below 133 and Groups IIA and HE having an atomic weight below 138 of the Periodic Chart of the Elements found at pages 58 and 59 of Langes Handbook of Chemistry, sixth edition (1964), published by Handbook Publishers, Inc., Sandusky, Ohio.

In a more specific embodiment of this invention, at least one of the selected metallic members is zinc.

Thus in this more specific embodiment there is added tothe vapor phase oxidation a small rutile promoting amount of aluminum and/or zirconium, a small, effective amount of a source of zinc, and a small, effective amount of a source of at least one other metallic member of the group consisting of potassium, rubidium, cesium, beryllium, magnesium, calcium, barium, strontium, cadmium, sodium, lithium, silver, and copper.

Specific combinations envisioned in the practice of this invention include not by way of limitation: a source of Al or Zr plus at least one source of Zn and K; a source of Al or Zr plus at least one source of Zn and Rb; a source of Al or Zr plus at least one source of Zn and Cs; a source of Al or Zr plus at least one source of Zn and an alkaline earth metal selected from the group consisting of Be, Mg, Ca, Sr, and Ba.

Rutile promoting agent as used herein is defined as a source of aluminum or zirconium.

Rutile promoting source is defined as any organic or inorganic compound of aluminum, zirconium, or both, including metallic aluminum or zirconium, which will react with oxygen at the vapor phase reaction temperature (of the titanium tetrahalide and oxygen) to form the corresponding metal oxide although it is not intended to indicate that the source material actually forms such oxide; that is, it is preferred that the source should in this instance be capable of forming the corresponding aluminum or zirconium oxides Whether or not such oxides actually are formed during the vapor phase oxidation reactionln addition, source as herein employed is further defined as also including the oxides of aluminum or zirconium providing such oxide is finely divided, e.g., having a mean particle size diameter of less than 1.0 micron, generally less than 0.5 micron, with best results obtained below 0.15 micron.

The source of the zinc and other metallic members selected from Groups IA, IB, IIA, IIB is defined as any organic or inorganic compound of the metallic members which contains one or more of the various members (including the metallic member in an elemental state), preferably a saline which will react with oxygen at the vapor phase reaction temperature'to form a corresponding oxide of the selected member although it is not intended to indicate that the source material actually forms such oxide; that is, the source should in this instance be capable of forming a corresponding oxide of the selected metallic member of Groups IA, IB, 11A, 11B whether or not such oxide actually is formed during the vapor phase oxidation reaction. In addition, source as herein employed is further defined as also including any oxide of the selected members providing such oxide has a mean particle size diameter in the range specified for the oxides of aluminum and zirconium hereinbefore.

In addition to additives of aluminum, zirconium, and the selected metals of Groups IA, 113, IIA, and IIB, noted hereinbefore, there may be further added a source of silicon.

Silicon source is defined as any organic or inorganic compound of silicon including elemental metallic silicon which will react with oxygen at the vapor phase reaction temperature to form the corresponding metal oxide although it is not intended to indicate that the source material actually forms such oxide; that is, the source should be capable in this instance of forming the corresponding silicon oxide, e.g., SiO whether or not such oxide actually is formed during the vapor phase oxidation reaction. In addition, source is further defined as including the oxides of silicon, such as silica, providing such oxide has a mean particle size below 1.0 micron in diameter as specified for the oxides of aluminum and zirconium hereinbefore.

To more specifically describe the process of this invention, reference is made to the drawing, and FIGURES 1 to 3, inclusive, which depict apparatus for practicing the process invention.

FIGURE 1 describes a diagrammatic cross-section view of a concentric orifice-annulus burner fitted in a furnace.

FIGURE 2 further illustrates the construction of the burner of FIGURE 1, representing a view along line II of FIGURE 1.

FIGURE 3 illustrates a diagrammatic cross-section view of a burner which may be fitted in the furnace of FIGURE 1 to produce pigmentary titanium dioxide according to the process of this invention.

Referring to FIGURES 1 and 2, reaction zone cham ber of furnace A comprises a concentric steel shell 1 and an internal lining of firebrick 5 (or other heat resistant insulation). At the lower part of furnace A is a conical bottom terminating at outlet 7. At the upper part of furnace A is a burner A.

Burner A is composed of three concentric tubes, 2, 3, and 4. Tube 3 is arranged so as to circumscribe tube 4 (forming annulus 6) and tube 2 is arranged so as to circumscribe tubes 3 and 4 (forming annulus 9). Each of the tubes 2 and 3 are evenly spaced from the wall of the tube it circumscribes. This is more clearly shown in FIG- URE 2, which shows the tube arrangement taken along line II of FIGURE 1.

In the operation of the reactor of FIGURES 1 and 2, an oxygenating gas typically preheated 900 C. to 1750 C. is fed to the upper opening in tube. 4, while an inert gas at room temperature up to the temperature of the oxygenating gas is fed tothe opening at the top if tube 3.

The inert gas may comprise chlorine, nitrogen, bromine, iodine, argon, helium, krypton, xenon, carbon dioxide, or mixtures thereof. Concurrently therewith, titanium tetrahalide is fed to the, opening at the upper part of tube 2. The titanium tetrahalide has a temperature of 140 C. to about 1200 C.

Referring to FIGURE. 3, burner B, which may be fitted in furnace A of FIGURE 1 in replacement of burner A, is composed of three concentric tubes annularly arranged. Central oxygenating gas tube 12 is circumscribed by tube 11, which in turn is circumscribed by tube 10 such that there is formed annuli 17 and 16. Tube 11 is provided with an annular lip 13 at its lower end and tube 10 is provided with annular lip 14, such that the titanium tetrahalide and inert gas streams are emitted from the annuli 17 and 16 in a direction substantially perpendicular to the direction of flow of the oxygenating gas from tube 12. In operation, burner B is fed in the same manner as burner A of FIGURE 1.

The source or sources of the various additives, e.g., aluminum, zirconium, metallic members of Groups IA,

IB, IIA, IIB, and silicon, can be introduced to the vapor phase reaction together or separately.

Furthermore, such sources can be introduced directly or indirectly to the vapor phase reaction of the titanium tetrahalide and oxygen.

Thus in the practice of this invention, one or more sources of one or more of the aforementioned additives may be added in conjunction with an inert gas, or one or more of the reactants, or both.

When the process is heated by the combustion of a fuel, one or more sources may be added to the fuel or the products of combustion thereof, e.g., a combustible carbon-containing or sulfur-containing fuel or the combustion products thereof when a process is operated in accordance with US. Letters Patents 3,069,282 and 3,105 742.

The source of each selected additive may also be added directly tov the reaction zone 30 independently of the reactants, inert gases, or combustible fuels; e.g., one or more sources may be added directly to the reaction zone as an atomized spray in a solid, liquid, or gaseous state.

Furthermore, one or more metallic additives may be added to the zone 30 by employing an inner furnace wall 5 constructed of a ceramic or firebrick material which contains one or more sources of one or more additives, e.g., one or more compounds of aluminum, zirconium, zinc, alkali metal, or alkaline earth metals. Such Source material is gradually eroded into the reaction zone due to the high temperature and corrosive nature of the environment in zone 30, as noted, for example, in British patent specification 672,753.

One or more additives, particularly potassium, may also be introduced into the reaction zone by employing a ceramic dedusting edge, as disclosed in copending US. application Serial No. 379,825, filed July 2, 1964, wh h contains a source of the particular additive, e.g., lava stone containing about 0.5 to 1.5 percent by weight potassium.

Likewise, the additive may be introduced to. the zone 30 by using a bafiie as disclosed in copending' U. S. ap plication Serial No. 376,980, filed June 22, 1964, which is constructed out of the. selected additive or a source of the additive.

Such sources may also be added directly to the, zone 30 or to one or more inert or reactant gas streams by emitting the source from one or more plasma arc elec trodes as disclosed, for example, in copending' patent application Serial No. 354,597, filed March 25, 1964.

The aluminum and/or zirconium source is added to the vapor phase oxidation reaction in an amount sai ficient to insure the presence of 0.5 to 10.0 mole percent of aluminum and/ or zirconium, basis the moles of titanium oxide formed; equivalent to about 0.17 to 3.38 percent by weight metallic, aluminum and about 0.57 to 11.40 percent by weight zirconium, based on, the weight of the titanium oxide pigment formed.

Best results are obtained when thev source of aluminum and/or zirconium is added in a, small, effective. amount equivalent to less than 3.0 percent by weight aluminum and less than 4.5 percent by weightv zirconium, based on the titanium oxide pigment formed.

Thev selected metallic source ('or sources) ofzinc and the other metallic members of Groups: IA, IB, HA, and 11B may be added to the vapor phase oxidation reaction in amounts ranging from 0.01 to 10,000 parts by weight of each selected metal ion per million parts by weight of titanium oxide obtained from the oxidation reaction. Generally, there is added less than 6,000 parts by weight of the metal ion with best results being. obtained with 5 to 5,000 parts by weight of the metal ion per million parts by weight of titanium oxide formed by the oxidation reaction. With certain selected highly active, metal ions such as potassium it may be. more. desirable to, add substantially less than 1,000 parts by weight per million parts by weight titanium oxide.

If silicon source is also added to the reaction, it is added in an amount suificient to insure the presence of 0.001 to 2.7, preferably 0.01 to 2, mole percent silicon, basis the moles of titanium oxide pigment product formed by the reaction; that is, 0.00035 to about 0.945, preferably 0.0035 to 0.70, percent by weight silicon ion based on the weight of the titanium oxide pigment formed. Although favorable results are obtained in the range of 0.2 to 1.2 mole percent silicon ion per mole of titanium oxide formed, equivalent to 0.07 to 0.42 percent by weight titanium oxide, best results being obtained particularly in the presence of aluminum and zinc or potassium ion when the silicon ion is added in a small, effective amount of less than 0.3 percent by weight, based on the weight of the titanium oxide.

The total metallic ions added to the reaction (e.g., Zr, Si, Zn, K, etc.) should not exceed percent by weight of the titanium oxide formed with more elfective results being obtained below 6.0 percent by weight. Best results are obtained below 4.0 percent.

Specific sources of aluminum include, not by way of limitation, metallic aluminum, organic and inorganic compounds containing aluminum including oxides, hydroxides, nitrates, nitrides, sulfides, sulfates, and halides such as Al(C H O (aluminum acetate), Al(OH)(C H O (aluminum acetate, basic), AlC H O (aluminum citrate), AlCl AlCl, AlBr AlBr, AlI AlI, AlF AlF, Al(ClO -6H O (aluminum chlorate), Al(OH) A1 0 Al(NO -9H O, Al N AI(SO A1 8 H AlF AlN the aluminum ammonium halides such as AlCl -NH NH Al(SO and aluminum containing esters, for example, aluminum compounds containing one or more organic ester radicals with one to ten carbon atoms per radical, e.g., Al(OC H (aluminum isopropylate or isopropoxide).

Likewise, there may be employed, not by way of limitation, aluminum compounds containing other organic radicals such as hydrocarbons, e.g. paraffius, cycloparaffins, olefins, acetylenes, aromatics, alcohols, phenols,

ethers, carbonyls, amines, and benzene rings. Furthermore, there may be used alloys of aluminum providing such alloys are capable of being oxidized. It may in some instances be necessary to use particular alloys in a finely divided state, e.g., of a particle size below 3.0 microns, in order to enhance oxidation.

Specific sources of zirconium include, not by way of limitation, metallic zirconium, organic and inorganic compounds containing zirconium including oxides, hydroxides, oxalates, nitrates, nitrides, sulfides, sulfates, halides, and oxyhalides such as ZrBr ZrCl ZrF ZrI Zr(OI-I) Zr-(NO -5HO, ZrO Zr(C O -2Zr(OH) (zirconium oxalate, basic), Zr(SO -4H O, ZrCl(OH) -3H O, ZrF(OH) -3H O, ZrBr(0H) -3H O ZrI( OH) 3H O, ZrOCl 8H O, ZrOF 8H 0 ZrOBr -8H O ZrOI -8H O, and zirconium compounds containing one or more organic radicals, e.g., hydrocarbons, esters, benzene rings, alcohols, olefins, etc., as listed for aluminum. There may also be used alloys of zirconium, providing such alloys are capable of being oxidized. Such alloys may necessarily have to be employed in a finely divided state as noted for the aluminum alloys.

The zinc ion source can be metallic zinc or a zinc compound. Examples, not by way of limitation, of zinc compounds include both organic and inorganic compounds such as Zn(C I-I O (zinc acetate), Zn(C H O -H O, ZnAl O (zinc aluminate), Zn(NH (zinc amide), ZH(C7H5O2)2 (zinc benzoate), 3ZnO-2'B O (zinc borate), Zn(BrO -'6H O (zinc bromate), ZnBr (zinc bromide), Zn(C H-;O -2H 0 (zinc butyrate),

(zinc caproate), ZnCO (zinc carbonate),

Zn(ClO -4H O (zinc chlorate), ZnCl (zinc chloride), ZnC-rO, (zinc (zinc tartrate), Zn(SCN) (zinc thiocyanate),

(zinc valerate), [Zn(NH )2]Cl (zinc diaminezinc chloride), Zn(CH CH OH CH (zinc di-n-butylzinc),

I 2 5)a (zinc diethylzinc), Zn(CH (zinc dimethylzinc),

. -ZH(C6H5)2' (zinc diphenylzinc), Zn(CH' CH- CH (zinc di-n-propylzinc), Zn (C H CH (zinc. di-o-toylzinc),

(zinc formate), ZnGa O (zinc -gallate), ZnC H O P (zinc glycerophosphate), Zn(OH) (zinc hydroxide) Zn(I0 (zinc iodate), Zn(IO -2H O, ZnI (zinc iodride),

Z11 (C3H302) 2 (zinc di-lactate), Zn(C I I O -2I- I Ov (zinc di-lactate), Zn(C H O (zinc laurate), Zn(Mi"1O -8H O (zinc permanganate), Zn(NO -3H O (zinc nitrate), ZnN (zinc nitride), ZnO (zinc oxide), Zl'l(C4H7'O2)2 (zinc acetylacetonate), .Zn(C H O.,) (zinc l-phenol-4-sulf0- nate, Zn (P0 (zinc ortho phosphate), Z113 2 ZH3(PO4)2'8H20, Z113 (P04)2'2H20, Zl'lgPzOq (ZinC p'yrophosphate), Zn P (zinc phosphide), Zn(H PO -H O (zinc hypophosphite), zinc picrate, Zn(C- H O -3H O (zinc salicylate), ZnSeO -5H O (zinc selenat I a ZnC O (zinc oxalate), zinc oleate, ZnSiO (zinc metasilicate), zin-c stearate, ZnSO (zinc sulfate); hydrates of zinc sulfate, ZnS, ZnS-H O, ZnS.O (zinc sulfite). Likewise, zinc alloys may be used. The cadmium ion source can be elemental cadmium or a cadmium compound, e.g., compounds similar to those for zinc listed hereinbefore. Cadmium compounds thus comprise both organic and inorganic including Cd (C H O 2 (cadmium acetate), Cd(BrO -H O, CdBI'z, I

CdCO

CdCl Cd(CN) 1 CdS O 6H O (cadmium dithionate) Cd- Fe CdF2, cd Hco ,-2H,o, Cd 2, Cd 3 )2,

Cd(C H 0 (cadmium lactate), s)2

CdO,

Cd O,

7o cdseo CdSe, CdSO CdSO -H 0, CdS, CdSO 7 cadmium alkali metal halides such as CdCl -4NH Cl and CdBr -4KCI,

Cd (COO) (cadmium oxalate), Cd(C H O -H O (cadmium salicylate),

as well as alloys of cadmium.

The potassium ion source can be elemental potassium or a potassium compound. Examples, not by way of limitation, of potassium compounds include both organic and inorganic compounds such as KHC H O (potassium saccharate acid),

KOC H NO -2H O (potassium-m-nitrophen oxide or potassium-p-nitrophen oxide),

KHC H O -C H O (potassium hydrogen succinate),

K 50 (potassium sulfate),

KHSO (potassium hydrogen sulfate),

K 8 (potassium pyrosulfate),

14 8 0 (potassium peroxydisulfate),

K S (potassium monosulfide),

KHS (potassium hydrosulfide),

K 8 (potassium disulfide),

K 8 (potassium trisulfide),

K 8 (potassium tetrasulfide),

K 8 (potassium pentasulfide),

KHSO

K C H O -VzI-I O (potassium d-tartrate),

KHC H O (potassium hydrogen d-tartrate),

K H TeO -3H O (potassium orthotellurate),

K CS (potassium trithiocarbonate),

KSCN (potassium thiocya-nate),

K 5 0 (potassium dithionate),

K 8 0 (potassium trithionate),

K S O (potassium tetrathionate),

2K S O 3H O (potassium pentathionate),

3K S O -H O' (potassium thiosulfate),

KHC H N O (potassium acid urate),

KC H -O (potassium acetate),

KC H O -HC H 0 (potassium acid acetate),

KNH' (potassium amide),

KNH C H O (potassium ammonium tartrate),

KN (potassium azide),

KC H O -3H O (potassium benzoate),

K B H (potassium diborane),

K BzH O (potassium di-hydroxy diborane),

K B H (potassium pentaborane),

KBO (potassium metaborate),

K2B4O7' 8H O (potassium tetraborate),

KB 0 4H O (potassium pentab orate) K130 /2H O (potassium peroxyborate) KC H BO (potassium borotartrate),

KBrO (potassium bromate),

KBr (potassium bromide),

KAUBI'4,

K CrO -2Cr(OH)CrO (potassium chromium chromate,

basic),

KCr(SO l2H O (potassium chromium sulfate),

K C H O -H O (potassium citrate),

KH2C6H507 (potassium citrate, monobasic),

KOCN (potassium cyanate),

KCN (potassium cyanide),

KC H SO (potassium ethyl sulfate),

K GeF (potassium fluogermanate),

K C H O (potassium fluoresoein derivative),

8 KPF (potassium hexafluorophosphate), KF (potassium fluoride), KF-2H O, KHF 5 )2,

KBF (potassium fluoborate), K HPO (potassium mono hydrogen orthophosphite), KH PO (potassium di hydrogen orthophosphite), KHC H O (potassium hydrogen phthalate), KC H N O' (potassium picrate), KC H O (potassium piperate), KC H O -H O (potassium propionate), KC H SO (potassium propyl sulfate), KHC H O (potassium acid-d-saccharate), KC H O (potassium salicylate), KC H O (potassium santoninate), KC H O (potassium stearate), K C H 0 3H O (potassium succinate), KHC H O (potassium hydrogen succinate), KHC4H4O4 ZHgO, KFSO (potassium fluosulfonate), K ThF 4H O (potassium fluothorate) K TiF H O (potassium fluotitanate KCHO (potassium formate), K C H PO (potassium glycerophosphate), KH (potassium hydride), KOH (potassium hydroxide), K10 (potassium iodate), KlO -HIO (potassium acid iodate), KIO3'2HIO3, K10 (potassium metaperiodate'), KI, K1 (potassium triiodide), KCl, KCl K KF3: KBr, KBI3, KC H O -xH O (potassium lactate), KC H O (potassium laurate), K C H O (potassium malate), K CH (SO (potassium methionate), 2KCH SO 'H O (potassium methyl sulfate), K C H (SO -2H O (potassium naphthalene-1,5-

disulfonate KIBr (potassium dibromoiodide), KgSIlBl's, K C H O SH O (potassium d-camphorate), K CO (potassium carbonate), KzCOg'XHzO, KHCO; (potassium hydrogen carbonate), K C 0 (potassium peroxy-carbonate), (KCO) (potassium carbonyl), K010 (potassium chlorate), KCIO, (potassium perchlorate), KClO, KICL, (potassium chloroiodate), KICI K OSC1 (potassium chloroosmate), K RhCl (potassium pentachlorohodite), K CrO (potassium chromate), KzCI'zO- (potassium dichromate), K CrO (potassium peroxychromate), KNO (potassium nitrate), K N (potassium nitride), KNOA (potassium nitrite), KC H O (potassium oleate), KC H O C H O (potassium acid oleate), 70 K OsO -2H O (potassium osmate),

K C O -H O (potassium oxalate), KHC O (potassium hydrogen oxalate), KHC2O4'1/2H2O, KHC204'H20, 75 KHC O -2H O,

KC H SO (potassium phenyl sulfate),

K lgO -3H O (potassium pyrophosphate),

Likewise, the corresponding compounds of other alkali metals such as sodium and lithium as well as cesium and rubidium may be used as sources of the respective ion, e.g., sodium, lithium, cesium, and rubidium.

Thus, the cesium ion source can be elemental cesium or a cesium compound similar to the K compounds noted hereinbefore. Examples, not by way of limitation of cesium compounds, include both organic and inorganic compounds as CsC H O (cesium acetate), CsOH-I (cesium benzoate), CsBrO- (cesium bromate), CsBr (cesium monobromide), CsBr (cesium tribromide), CsBrClI (cesium bromochloroiodide), CsIBr (cesium dibromoiodide), CsI Br (cesium bromodiiodide), Cs CO (cesium carbonate), CsHCO (cesium carbonate hydrogen), CsClO (cesium chlorate), CsClO (cesium perchlorate), CsCl (cesium chloride), C-sAuCL, (cesium chlo roaurate), CsBr Cl (cesium chlorodibromide), CsBrCl (cesium dichlorobromide), CsICl (cesium dichloroiodide), Cs SnCI (cesium chlorostannate), Cs CrO (cesium chromate), CsCn (cesium cyanide), CsF (cesium fluoride), CsCHO (cesium formate), CsCHO-H O, CsH (cesium hydride), CsOH (cesium hydroxide), CsIO (cesium iodate), CsIO (cesium metaperiodate), CsI (cesium monoiodide), CsI (cesium triiodide), CsI (cesium pentaiodide), CsCl CsBr CsF CsNO (cesium nitrate), CsNO -HNO (cesium hydrogen nitrate), CsNO -2HNO (cesium dihydrogen nitrate), CsNO (cesium nitrite), Cs C O (cesium oxalate), Cs O (ceseium monoxide), C5 0 cesium peroxide), C5 0 (cesium trioxide), Cs0 (cesium superoxide), CsHC H O (cesium hydrogen phthalate), CsRh(SO -12H O (cesium rhodium sulfate), CsC H O (cesium salicylate), Cs SO (cesium sulfate), CsHSO (cesium hydrogen sulfate), Cs- S-4H O (cesium sulfide), Cs S (cesium disulfide), Cs S -H O, Cs S (cesium tetrasulfide), C5 8 (cesium pentasulfide), Cs S (cesium hexasulfide).

The rubidium ion source can be elemental rubidium or a rubidium compound, eg, similar tothe potassium and cesium compounds noted hereinbefore. Examples, not by Way of limitation of rubidium compounds, include both organic and inorganic compounds such as RbC H O (rubidium acetate), RbAl(SO l2H O (rubidium aluminum sulfate), RbBrO (rubidium bromate), RbBr (rubidium bromide), RbBr5 (rubidium tribr'omidei),

RbIBrCl (rubidium bromochloroiodide), RbIBr (rm- Rb O (rubidium trioxide), RbO (rubidium superoxide),

Specific sources of sodium or lithium ion would include elemental sodium and lithium as well as compounds of all the classes listed for potassium, cesium, and rubidium hereinbefore, particularly the halides and oxides.

Likewise, alloys or ceramics containing one or more of the Group IA elements may be employed, particularly where such alloy or ceramic is in a finely divided state.

Specific sources of the Group IIA metals include the metals in an elemental state as well as organic and inorganic compounds including the acetates, amides, borides, bromates, halides (including chlorides, iodides, bromides, fluorides), oxyhalides, carbonates, chlorates, chromates, citrates, hydrides, sulfides, sulfates, hypochlorites, nitrates, nitrites, oxides, silicates, aluminates of beryllium, magnesium, calcium, barium, and strontium. Alloys may also be employed as noted for the Group IB metals.

Sources of the Group IB metals, copper and silver, include the metals in elemental state, alloys, organic and inorganic compounds including the hydrides, nitrides, peroxides, suboxides, acetates, halides, sulfates, sulfides, bromates, esters, and nitrates such as CU(C H O (cupric acetate), CuCl -2NH Cl-2H O (cupric ammonium chloride), CuSO -4NH -H O, Cu(BrO -6H O, CU3B2, CUZHZ, C11 N, CUOZ'HQO, GU40, CuCl, CHQCIQ, CuBr, Cu Br CuI, Cu l CuF, Cu F CuSCN, (C H COO) Cu-2H O (copper benzate) and AgNO Ag O, AgCl, AgBr, Agl, AgF, AgBrO CH COOAg (silver acetate), Ag Cr O- KAg(CN) and silver phenolsulfonate.

Specific silicon compounds include, not by way of limitation, metal silicon, organic and inorganic compounds such as the silicon hydrides or silanes such as SiH, (monosilane), Si H (disilane). Si H (trisilane), Si H (tetrasilane), Si H (pentasilane), Si H (hexasilane), Si I-I Si H Sl9H2o, si Hzz; alkylsilanes such as CH SiI-I (monomethylsilane), (CH SiH (dimethylsilane),

(trimethylsilane) C H SiH (monoethylsilane) z s) z z \(diethylsilane), (C H SiH (triethylsilane), (CH Si (silicon tetramethyl), (C H Si (silicon tetraethyl), a 'fl a 3 'z)2 2 3 'I)3 13 14 e 5)2 z p y i Likewise, one or more compounds may be employed ('P- s Dz Qz (d p r m p yl i l n as a source of one or more additives, for example, e slz -r p y si Al (SiF (aluminum silicofluoride), CsAl(SO -12H O (l w q'lz mz -ply a (cesium aluminum sulfate), KAgBr KAg(CN) K SiF (C H CH SiCl (dibenzyldichlorosilane), 5 (potassium fluosilicate), K SiO (potassium metasilicate), 2=. H)( H3) 2 (Vinylmethyldichlorosilane), K Si O (potassium disilicate), KHSi O (potassium hyr zH QS h y y il drogen disilicate), K 'ZrF (potassium fluozi-rconate), C H (n-C H )SiCl (ethylpropyldichlorosila KCl-CaCl (potassium calcium chloride), CsSiF (cesium 2 5( 4' 9)SiCl (ethylisobutyldichlorosilane), fluosilicate), Al Ti AlCl -%ZnCl AlCu, AlCu Al Cu, 2 5( 6 5) 2 y p y n 10 CaZn CaSiO CaSi, CaAgC N cdsio and C H (C H CH )SiCl (ethylbenzyldiohlorosilane), C d1 O C H (C H CH )SiClg (phenylbenzyldichlorosilane), 2 2 C H (p-BrC H )SiCl (phenyl-p-bromophenyldichloro- Furthermore, there may be employed alloys containsilane), v a ing one or more of the aforementioned additives, such CH SiCl (methyltrichlorosilane), as Ag-Cu alloys, particularly an alloy containing 80% C H SiC1 (ethyltrichlorosilane), Ag- Cu, by weight. OH =CHSiCl (vinyltrichlorosilane), Among the above sources listed for aluminum, zirn-C H SiCl .(propyltrichlorosilane), conium, the metallic members of Groups IA, IB, IIA, CHFCHCH SiCl (allyltrichlorosilane), and HE, and silicon, there are certain advantages which n-C H SiCl (-butyltrichlorosilane), 20 will accrue from the use of certain classes of material, i C H SiCl (isobutyltrichlorosilane), for example, the halides, particularly the chlorides. i-C H 'SiCl (isoamyltrichlorosilane), It is particularly advantageous to conduct the vapor C H SiCl (phenyltrichlorosilane), I I phase oxidation in the presence of sources which will e n a (W y lorosilane), react with oxygen at the temperature of the vapor phase p:C H SiCl (p-tolyltrichlorosilane), oxidation to form the corresponding metal oxide. It is C H CH SiCl (benzyltrichlorosilane), not intended to indicate that the source materials herein a-C I-I SiCl (a-naphthyltrichlorosilane) listed for aluminum, zirconium, silicon and the mem- CH SiBr (methyltribr'omosilane), bers of Groups IA, IB, IIA, IIB must actually form the (CH SiOH, (CH Si (hexamethyldisilane), corresponding metal oxide during the vapor phase oxida- (-C H Si (hexaethyldisilane), I tion. However, it is advantageous if the source material (C3H7) Si2 (hexa-n-propyldisilane), in this instance is capable of forming a metal oxide, (C H (C H (C H Si (diethyldipropyldiphenyldiregardless of whether such oxide is formed.

sil'ane), Where a metallic source is a high ioniza-ble salt such 2 5)2( 3 7)2( 7 q)2 i2 yldipropyldibenzyldias-KCl, NaCl, LiCl, BeCl RbCl, CsCl, it is not necessilane), sary for such compound to be capable of forming an (C H Si (hexaphenyldisilane), I oxide at the vapor phase oxidation temperature; that is, (C7H7)5Si2 (hexa-p-tolyldisilane or hexabenzyldisilane), g resultsnafe. Obtained y the a i of a g y (C H5) Si (octaphenyltetrasilane), ionizable. source which is not oxidized at the reaction s rJz h (W ctaphenyltetrasilane), temperature and which remains substantially unchanged (C H,,) Si l l t il chemically, e.g., as analyzed in an efiluent stream from [(P- 'z 'z)2 ]4 y c a-p-tolyltetrasilane), the reactor. Thus, when KCl is added to the vapor phase (C H Si O (hexa ropyldi il a j reaction of TiCl and 0 it is not oxidized but may be (C H Si O (hexaethyldisiloxane, recovered as KCl. f s)s z examethyldisilazane, Furthermore, it is also feasible to employ sources which (CI-I Si O (hexamethyldisiloxane), are not highly ionizable and which do not form oxides (C H Si O (cyclooctaphenyltetrasilane oxide or diat the Vapor Pha'Se Oxidation temperature Particularly if o id such sources are heated to a high temperature by passage (C H O) (C H Si (.C H $i (hexaisoamyldiw J through a plasma arc, e.g., in thepresence of an inert siloxane), as or one of the reactants such as oxygen. (C l-19 51 0 v (hexaphenyldisiloxane), The sourceslisted hereinbefore may be introduced into (C H Si O (hexa-p-tolyldisiloxane), the reaction chamber 30 very effectively as solutions in a .(CH C I-I' Si O (dimethyltetraphenyldisiloxane), Solvent, e.g., in the form of a spray. Thus, water soluble (C H (CgH Si O (diethyltetraphenyldisiloxane),' metal sources of the type herein contemplated can be C H n-C I -I Si O (diethyldipropyldibenzyldi- I used in' water solutions. Oganic',m'etal sources may be flo v "55 used in many cases where they are liquids or gases, or ..(C H (i- 4 s)2( 7H7)2 zQ .(diethyldibutyldib z l'., may be used in solutions in common organic solvents di il a which are, not adverse to the vapor phase oxidation. (C H Si O(OH) ,(t traphenyldisiloxaner1,3-diol), Typical solvents are chlorofiorm, methylene chloride, CgH )gSi5O (OH) (hexaphenyltrisiloxane-1,5-diol), or like chlorinated aliphatic or aromatic solvents; Other 1 H' C 1-I -(digthyldipheny1disi1oxane typical solvents include -acet'ones,'ketones, =benzenes,j and IB-di li. 1 ;v i 1; a o 'I 'IM Z z Y i It is also advantageous'to use materials which vaporize C 0 H (hexabenZYltrisiloxane-1',5;dio1), readily and can be introduced in a vapor state-Thus, z h ethylcyclotrisiloxane), zinc metals and various zinc halides are advantageous .(Et SiO), (hexaethylcyclotrisiloxane), f. f -65,Which are volatile at the vapor phase reaction temper- (C H Si 'O (hexaphenylcyclotrisiloxane), ature- (YCGHQBSLO4 (octaphgnylcyclotetrasiloxane) The following is a typical working example representing :(CHHHGSEQ, (hx b z l l tfi il n H the best mode contemplated by the inventor in the carry- (EtBzSiO) (triethyltribenzylcyclotrisiloxane). 1 76 mg Outof thls'inventim a v Inaddition,-applicantincorporates herein by reference Example 'all'of the silicon compounds listed on pages 166 to 195 A burner having the configuration of burner B in FIG- of Silicones and Other Organic Silicon Compounds, URE 3 is employed in conjunction with reaction chamber by'Howar'd W. Post; Reinhold Publishing Corporation, A of FIGURE 1. New York (1949). it a e -Titanium tetrachloride ..(TiCl at 1000 C. and 14.7

15 16 pounds per square inch absolute pressure is flowed at the Conversely, the more brown the pigment, the less pleasing rate of 80 millimoles per minute through annulus 17 into the optical properties of the paint. reaction zone 30. The TiCL, contains 3 mole percent of The undertone scale to be used ranges from a Brown AlCl based on the total moles of TiC1 10 to a Blue 6 as shown hereinafter in Table II.

Simultaneously, oxygen at 1000 C. and 14.7 pounds TABLE II per square inch absolute pressure is flowed at 96 milli- Brown Brown 1 moles per minute through passage (tube 12) into the Brown 9 Neutral reaction zone 30. Brown 8 B1 u e 1 A 40 mole percent chlorine shroud (based on the total 0 Brown 7 Blue 2 (Standard) moles of T1Cl at 1000 C. and 14.7 pounds per square 10 Brown 6 Blue 3 inch absolute pressure is flowed through annulus 16. Brown 5 Blue 4 The reaction zone 30 is preheated and maintained at 4 B1 5 1000" c. B'mwn 6 Varying amounts of different ions from Groups IA, gigz 3 B IB, IIA, IIB are added to the oxygen stream. The AlCl 15 n addition to the TiCL, is held constant at 3 mole percent. While the invention has been described by reference All ions were added as chlorides, e.g., KCl, CsCl, RbCl, to specific details of certain embodiments, it is not in- BaCl BeCl AgCl, ZnCl and SiCl tended that the invention be construed as limited to such The titanium oxide pigment formed in zone 30 is withdetails except insofar as they appear in the appended drawn at exit 7 entrained in a gaseous effluent stream. claims. The raw pigment is recovered and is wet coated with Iclaim: hydrous alumina and titania in accordance with the proc- 1. A process of preparing pigmentary titanium oxide, ess of US. Letters Patent 3,146,119 issued to Dr. Hartien which comprises reacting a titanium tetrahalide selected S. Ritter. from the group consisting of titanium tetrachloride, The results are tabulated in Table I All additives are titanium tetrabromide, and titanium tetraiodide with an expressed in parts by weight of the particular metallic oxygenating gas in the vapor phase in the presence of an ion per million parts by weight titanium oxide pigment effective amount of at least one rutile promoting agent, formed. an effective amount of zinc ion, an effective amount of Both raw and coated tinting strength (T.S.) are given a metallic ion selected from the metals of Groups IA, for the pigment, as well as raw and uncoated tint tone IB, and IIA, and cadmium, and an effective amount of (T.T.). a source of silicon ion.

TABLE 1 Run Additives t0 O;,p.p.m. Pigment, Pigment, Pigment, Pigment, No. Titanium Oxide Raw Coated Raw Coated 'I.S. '1.s. T11. TJI.

1, 500 4,000 211,100 K.. 1, 720 3,000 Z11, K. 1, 710 3,500 Zn, 100 K- 1, 710 3, 500 Zn, 1 000 Cs 1, 000 2,000 Rb, 100 K. 1, 700 2,000 Rb, 1,000 O 1, 700 2,000 Os, 100K 1,710 4,000 Zn, 100K, 2,000 $1... 1, 750 4,000 211,3,000 Ba. 1, 690 1,750 Brown 2. 4,000Zn, 3,000 Be 1,700 1,700 Neutral 1,700 1,700 1,710 1,780 Blue 1,710 1, 770

The tinting strength of pigmentary titanium dioxide 2. A process according to claim 1 wherein said metallic may be determined by any oi several methods known in ion is potassium ion. the paint industry. One such method is the Reynolds Blue 3-. A process according to claim 1 wherein said rutile Method, A.S.T.'M. D3 322.6, 1949 Book of A.S.T.M. promoting agent is a source of aluminum ion. Standards, part 4, page 31, published by American 4. A process according to claim 1 wherein the total Society for Testing Material, Philadelphia 3, Pennsylamount of rutile promoting agent and other metallic ions "vania. does not exceed 10 weight percent, basis titanium oxide Tint tone or undertone of. a titanium dioxide pigment formed- :sample is determined. by visuually comparing a paste of 5'. A process of preparing pigmentary titanium oxide the pigment with a paste oia selectedstandard. 0 having improved pigmentary properties, which comprises In the example hereinbefore, a paste of'a sample from reacting a titanium tetrahalide selected from the group each run. anda paste. of a. standard is. prepared in acconsisting of titanium tetrachloride, titanium tetracordance with A.S.T.M. D..3 3236 using carbon black bromide, and. titanium tetraiodide with an oxygenatlng to tint each sample paste to the same depth of grey as gas in the vapor phase at a temperature of at least 800 the standard. C. in the presence of:

The standard used has an oil absorption rating of 20.9 (a) from 0.5 to 10.0 mole percent, basis moles of as determined by A.S.T.M-. D.-28131, an average partitanium oxide, of a metal ion selected from the ticle size of- 0.25 micron as determined. with an electron group consisting of aluminum and zirconium ion, micrograph, and an assigned undertone value of Blue 2. (b) from 0.01 to 10,000 parts, per million parts of The samples obtained from the runs in the example are titanium oxide, of zinc ion, compared with the standard and an undertone value (c)- from 0.01 to 10,000 par-ts, per million parts of assigned to the sample. by stating; whether the sample is titanium oxide, of a metallic ion selected from the bluer or browner than the designated standard. metals of Groups-IA, IB, and HA, and cadmium, and

The more blue a pigment is, the more pleasing are the (d) from 0.001 to 2.7 mole percent, basis moles of optical, properties of a paint prepared fromthe pigment. titanium oxide, of silicon ion.

6. A process according to claim 5 wherein said metallic ion selected from the metals of Groups IA, IB, and HA, and cadmium is potassium ion.

7. A process of preparing pigmentary titanium oxide which comprises reacting a titanium tetrahalide selected from the group consisting of titanium tetrachloride, titanium tetrabromide, and titanium tetraiodide with oxygen in the vapor phase at a temperature of at least 800 C. in the presence of:

(a) from 0.5 to 10.0 mole percent, basis moles of titanium oxide, of a metal ion selected from the group consisting of aluminum and zirconium ion,

(b) from 5 to 5,000 parts, per million parts by weight titanium oxide, of zinc ion,

() from to 5,000 parts, per million parts by weight titanium oxide, of potassium ion, and

(d) from 0.01 to 2 mole percent, basis moles of titanium oxide, of silicon ion; such that the total amount of said metallic ions does not exceed weight percent, basis titanium oxide formed.

8. A process according to claim 7 wherein the total amount of metallic ions does not exceed 4.0 weight percent, basis titanium oxide formed.

9. A process of preparing pigmentary titanium oxide of improved tinting strength and tint tone which comprises reacting titanium tetrachloride with oxygen in the vapor phase at a temperature of at least 800" C. in the presence of 0.5 to 3.0 mole percent, basis titanium oxide, of aluminum chloride, 5 to 5,000 parts per million parts titanium oxide of potassium ion, 5 to 5,000 parts per million parts titanium oxide, of zinc ion, and from 0.2 to 1.2 mole percent, basis titanium oxide, of silicon ion.

10. A process according to claim 9 wherein the source of potassium, zinc, and silicon are their respective chlorides.

11. A process of preparing pigmentary titanium oxide of improved tinting strength and tint tone which comprises reacting titanium tetrachloride with oxygen in the vapor phase at a temperature of at least 800 C. in the presence of 3 mole percent of aluminum chloride, basis titanium oxide, 4,000 parts per million parts of titanium oxide of zinc ion, parts per million parts of titanium oxide of potassium ion, and 2,000 parts per million parts of titanium oxide of silicon ion.

12. In a process of preparing pigmentary titanium oxide wherein a titanium tetrahalide selected from the group consisting of titanium tetrachloride, titanium tetrabromide, and titanium tetraiodide is reacted in the vapor phase at a temperature of at least 800 C. with oxygen, the improvement which comprises carrying out said reaction in the combined presence of:

(a) from 0.5 to 10.0 mole percent, basis moles of titanium oxide, of a metal ion selected from the group consisting of aluminum and zirconium ion,

(b) from 0.01 to 10,000 parts, per million parts of titanium oxide, of metallic zinc ion,

(c) from 0.01 to 10,000 parts, per million parts of titanium oxide, of a metallic ion selected from the metals of Groups IA, IB, and IIA, and cadmium, and

(d) from 0.001 to 2.7 mole percent, basis moles of titanium oxide, of silicon ion.

References Cited UNITED STATES PATENTS 2,957,753 1 0/1960 Nelson et al. 23202 2,980,509 4/ 1961 Frey 2320=2 3,068,113 12/1962 Strain et al. 23202 3,208,866 9/1965 Lewis et al. 23202 X 3,214,284 10/ 1965 Wilson 10'6-300 OSCAR R. VER'I IZ, Primary Examiner. EDWARD STERN, MILTON WEISSMAN, Examiners. 

1. A PROCESS OF PREPARING PIGMENTARY TITANIUM OXIDE, WHICH COMPRISES REACTING A TITANIUM TETRAHALIDE SELECTED FROM THE GROUP CONSISTING OF TITANIUM TETRACHLORIDE, TITANIUM TETRABROMIDE, AND TITANIUM TETRAIODIDE WITH AN OXYGENATING GAS IN THE VAPOR PHASE IN THE PRESENCE OF AN EFFECTIVE AMOUNT OF AT LEAST ONE RUTILE PROMOTING AGENT, AN EFFECTIVE AMOUNT OF ZINC ION, AN EFFECTIVE AMOUNT OF A METALLIC ION SELECTED FROM THE METALS O FGROUPS IA, IB, AND IIA, AND CADMIUM, AND AN EFFECTIVE AMOUT OF A SOURCE OF SILICON ION. 